1. Field
Example embodiments relate to a method of aligning a wafer stage and an apparatus for performing the same. More particularly, example embodiments relate to a method of aligning a wafer stage on which a wafer may be arranged during an exposing process, and an apparatus for performing the method.
2. Description of the Related Art
Generally, a semiconductor device may be manufactured by various processes such as a deposition process, a patterning process, an ion implantation process, etc. A desired pattern may be formed on a wafer by the patterning process.
The patterning process may include a process for forming a photoresist film on a layer, an exposing process for irradiating a light to the photoresist film through a reticle, and a developing process for developing the exposed photoresist film to form a photoresist pattern. The layer may be etched using the photoresist pattern and an etch mask to form the desired pattern on the wafer.
In order to accurately form the desired pattern, it may be required to precisely align the wafer on a wafer stage with the reticle over the wafer stage.
In a related method of aligning the wafer stage, the wafer stage may be moved to a desired position using a linear motor. The position of the wafer stage may be measured using an interferometer. The interferometer may be arranged along a driving direction of the linear motor. That is, the interferometer may be arranged parallel with the moving direction of the wafer stage. The interferometer may irradiate a light to the wafer stage. The interferometer may receive a light reflected from the wafer stage to measure the position of the wafer stage.
However, as the semiconductor device may have been highly integrated, a design rule of the semiconductor device may also become narrower. Thus, it may be required to accurately measure a position of the wafer stage.